MGD S4 - DNA replication, Cell division and Inheritance

Question 1

What is the role of the cell cycle?

Answer 1

Mitosis division used in growth and repair

Contains several key checkpoints to prevent improper cell division

Question 1

What are the stages of the cell cycle? (Names only)

Answer 1

G1
S
G2
Mitosis

Question 3

What’s occurring during S phase of the cell cycle?

Answer 3

Chromosomes duplicate to form classical X shape (2 chromatids)

Question 3

At happens in G1 phase of the cell cycle?

Answer 3

Cellular content replication

Question 4

What happens during G2 phase of the cell cycle?

Answer 4

DNA is checked for errors and corrected

Question 4

At happens during the mitosis phase of the cell cycle?

Answer 4

The cell divides creating two genetically identical daughter cells.

Question 5

Define genotype

Answer 5

The genetic makeup of an individual

Can also refer to a specific genetic loci

Question 5

Define phenotype

Answer 5

All observable expressed traits as a result of genotype

Can also refer a specific trait arising from a single genetic loci

Question 6

Are gametes haploid or diploid?

Answer 6

Haploid

Question 6

What environmental factors may affect genotype and phenotype?

Answer 6

Radiation
Mutagens
Chemicals that affect cell growth
Diet Lifestyle (phenotype only)
Trauma (phenotype only)

Question 7

How does meiosis I differ from mitosis?

Answer 7

Instead of lining up along the equator single file, they line up in homologous pairs and are split into two sets of full (2 chromatids) chromosomes.

Question 8

What sort of genetic disease affects 25% of two carriers offspring?
Give an example

Answer 8

Autosomal recessive

Cystic fibrosis

Question 8

Name the three types of sex linked inheritance.

Answer 8

X linked dominan
tX linked recessive
Y linked

Question 9

Define the term ‘allele’

Answer 9

Refers to the different forms of a gene. Every individual has two alleles of the same gene, can either be the same or different.

Question 10

Define the term ‘gene’

Answer 10

A unit of heredity, length of DNA that codes for a protein as well as the necessary sequences for it’s expression such as promoter and terminator sequences and introns

Question 10

What is autosomal inheritance?

Answer 10

Inheritance of a gene on a non sex linked chromosome (autosome)

Question 11

What is meant by co-dominance in reference to alleles/traits?
Give an example of co-dominance

Answer 11

Both alleles are expressed in the phenotypic trait of heterozygotes.
Eg. AB blood type

Question 11

Explain the basis of co-inheritance of genes.

Answer 11

Genes on the same chromosome are likely to be inherited together
However the process of crossing over in meiosis will separate genes previously on the same chromosome.
Additionally, genes located close to one another on the same chromosome are said to be LINKED, less likely to be separated in crossing over.
Genes further away from each other more likely to be separated. Behave almost like unlinked.

Question 12

What sort of genetic disease effects one person of every generation?
Give an example.

Answer 12

Autosomal dominant

Marfan’s syndrome

Question 14

What is sex linked inheritance?

Answer 14

Inheritance of a gene on the X or Y chromosome

Question 15

Haemophilia is an example of what type of genetic disease?

Answer 15

X linked recessive

Question 15

What sort of genetic disease only affects males?

Answer 15

Y linked, passed from father to son.

Question 16

Explain what is meant by ‘dominance’ of an allele/trait.

Answer 16

The phenotypic trait is expressed in homozygotes and heterozygotes

Question 16

Explain what is meant by the term ‘recessive’ for alleles/traits.

Answer 16

Phenotypic trait appears only in homozygotes